JPH026516Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) This invention relates to a pinch roller that clamps a magnetic tape between a capstan and a capstan that is driven to rotate forcibly in a tape recorder, VTR, etc., and controls the transfer of the magnetic tape.

(General technical issues) Pinch rollers must have the ability to rotate as smoothly as possible, but it is also essential that they have an automatic centering function to ensure stable tape running. be. In other words, if the centering function is not provided or is insufficient, the transfer tape may be biased or elongated due to errors in the parallelism of the axes of the capstan and pinch roller, which are unavoidable due to design and manufacturing. In severe cases, the tape may come off the pinch roller, or the tape may fluctuate up and down or the running speed may fluctuate, increasing the amount of wow and flutter.

(Prior art) The most common structure of conventional pinch rollers is a cylindrical sleeve with an elastic tire made of rubber or other material fixed to its outer circumferential surface, which is rotatably supported on a roller shaft via a ball bearing. . However, in this case, not only does the production cost of the pinch roller become high due to the fact that the ball bearing described above must be extremely precise and compact, but also the smoothness of rotation is generally affected due to uneven precision of the anti-friction balls. It was difficult to obtain sufficient satisfaction. In addition, the above-mentioned ball bearings attempt to achieve the desired self-aligning effect by utilizing the clearance between the anti-friction balls and the inner and outer rings of the bearing, which would otherwise cause harmful rattling. As a result, the amount of automatic alignment was small, and the alignment function was not smooth.

As one means to solve these problems, recently, a spherical part centered on the axis of the roller shaft has been formed on the inner peripheral surface of the metal sleeve, as shown in Japanese Patent Application Laid-Open No. 155559/1983. On the other hand, a spherical part corresponding to the above is formed on the lower outer peripheral surface of the bearing metal made of a sintered oil-impregnated alloy that is rotatably and slidably fitted onto the roller shaft, and a self-aligning effect is achieved by sliding contact between both spherical parts. A pinch roller has been proposed to achieve this. However, in this conventional technology, in order to hold the bearing metal in a predetermined position, it is necessary to install a coil spring or the like to elastically restrain the bearing metal from above. This may cause relative displacement in the vertical direction, which not only poses some problems with the stable tape transfer function, but also causes rotational support due to the direct sliding contact between the spherical parts of the bearing metal and the sleeve. Because it performs automatic alignment,
The sliding contact surfaces are subject to severe wear, causing harmful rattling relatively early, and the frictional noise caused by the sliding contact adversely affects audio characteristics such as wow and flutter.

(Purpose of the invention) The purpose of this invention is to solve all the various problems of the prior art as described above. In other words, both the rotary support and self-alignment functions can be made extremely smooth, without adversely affecting audio characteristics such as wow and flutter, increasing the service life, and improving the control range of self-alignment. It is an object of the present invention to provide a structure of a pinch roller that can have a large size, and can also be manufactured easily including processing and assembling the members, thereby achieving a reduction in manufacturing costs.

(Configuration and Examples) The configuration of this invention will be described below based on illustrated examples.

Reference numeral 1 denotes a roller shaft, and 2 a short cylindrical bearing fitted in the longitudinally intermediate portion of the roller shaft, which is supported on an annular collar portion 1a integrally formed on the outer circumferential surface of the roller shaft 1. In addition, this bearing 2 has an outer peripheral surface that is similar to the roller shaft 1.
It is formed in a spherical surface part 2a with the center O placed on the axis l of. Of course, this spherical surface portion 2a only needs to be formed on at least both the upper and lower portions of the outer circumferential surface, and the intermediate portion thereof may be formed on a vertical surface 2b parallel to the axis l, as shown by the chain line in FIG. Also good.

3 is a cylindrical metal sleeve, 4 is a cylindrical elastic body made of synthetic rubber or the like fixed to the outer peripheral surface of the sleeve, and 5 is a cylindrical bearing holder that is tightly fitted and fixed in the sleeve 3; An annular groove 6 having a substantially trapezoidal cross section is formed on the inner circumferential surface, into which the outer circumferential surface of the bearing 2 is loosely fitted, forming a sleeve 3 with the center O as a fixed point, as shown in FIG. The predetermined angle θ
It is designed to allow tilting movement (self-aligning behavior) within this range.

By the way, the bearing 2 and bearing holder 5 are as follows:
One of them is made of a permanent magnet, and the other is made of a magnetic material. Thus, in the illustrated embodiment,
For manufacturing advantages, the bearing 2 is made of a magnetic material, and the upper and lower ends of its outer peripheral surface are magnetized with N and S poles as shown in the figure, and the bearing holder 5 is made of a magnetic material. It is said that it was formed in The spherical portions 2 of both of these 2 and 5
A lubricating magnetic fluid 7 which is attracted and held by the magnetic force of the magnet body, that is, the bearing 2, is interposed between the close opposing surfaces of the annular groove a and the inner surface of the annular groove 6.

The magnets used here include alnico magnets,
Ferrite magnets, resin magnets, etc. can be used as examples, and among them, resin magnets are particularly advantageous in terms of moldability, ease of manufacture, mass productivity, and the like. This resin magnet is made by kneading ferromagnetic powder and thermoplastic or thermosetting resin, molding it, and magnetizing it at the required locations.The ferromagnetic powder has the general formula MOm (Fe ₂ O ₃ ), for example. n [However, M is Ba,
Ferrite represented by one or more of Pb, Sr, Ca and Co, where m and n are positive integers], or with the general formula RCo ₅ or R ₂ Co ₁₇ [however, R
is one or more of Sm, Y, Ld, and Co] and the like is used. Further, as the resin, thermoplastic resins such as polyamide resin, polyethylene resin, and polyethylene terephthalate resin, or thermosetting resins such as epoxy resin, unsaturated polyester resin, and phenol formaldehyde resin are used. The blending ratio of the ferromagnetic powder and synthetic resin, other molding conditions, etc. are in accordance with conventionally known methods.

On the other hand, as the magnetic material, an alloy such as iron or stainless steel may be used, but it is most preferable to use a resin magnetic material for reasons such as ease of molding as described above. The resin magnetic material has a magnetic permeability of approximately 4000 to 100, which is obtained by kneading and molding a magnetic powder with a small coercive force with a synthetic resin in the same manner as described above.
Here, the magnetic powder includes powders such as Fe, Ni, Co, etc., or the general formula MOm(Fe ₂ O ₃ ) n [where M is
A soft magnetic powder or the like represented by one or more of Mn, Zn, Cu, Ni, Mg, etc., where m and n are positive integers, etc., is used.

Further, the magnetic fluid 7 is composed of magnetic particles dispersed in oil via a surfactant, and functions as a lubricant.

Further, the bearing holder 5 is constituted by a combination of an upper hole 5a and a lower holder 5b which are divided into upper and lower halves, with the horizontal plane where the center O of the spherical portion 2a of the bearing 2 is located as the dividing plane. By configuring the bearing holder 5 into two parts in this way, during assembly production, the lower holder 5b is fitted and fixed in the sleeve 3 in advance, and then the roller shaft 1 with the bearing 2 mounted thereon is fitted into the sleeve 3 from above. Then, by fitting the upper holder 5a into the sleeve 3, the pinch roller can be easily assembled. In addition, in the figure, 8 is a washer, and 9 is an E-ring that holds it in place.

(Operation and Effect) Since this invention has the above-described configuration, the cylindrical elastic body 4, the sleeve 3, and the bearing holder 5 are integrated around the bearing 2 fitted to the roller shaft 1. While rotating, the spherical portion 2a of the outer peripheral surface of the bearing 2 is fitted into the corresponding annular groove 6 of the bearing holder 5 in a state that allows relative tilting behavior, thereby forming a kind of spherical universal joint. As a result, the self-aligning action of freely tilting and displacing the outer circumferential surface of the roller in the axial direction within a predetermined angular range can be realized over a relatively large control range. Moreover, the bearing 2 and the bearing holder 5 are
Each of them is composed of a magnet body and a magnetic body, and a magnetic fluid 7 that is attracted and held by the magnetic force of the magnet body is interposed between their close opposing surfaces. Not only can the core function smoothly, but also its wear can be significantly reduced. In addition, by magnetically adsorbing the magnetic fluid, a small amount of magnetic fluid can be kept reliably in the effective working area at all times, and together with this, it maintains good rotational performance and self-aligning performance over a long period of time. Durability can be greatly improved, and there is less risk of adverse effects on audio characteristics such as wow and flutter due to rattling. Furthermore,
The number of component parts is small, manufacturing is simple, and compared to the case where expensive ball bearings are used, the parts cost is lower and can be manufactured and provided at a lower cost.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention; FIG. 1 is a longitudinal sectional view, and FIG. 2 is an enlarged sectional view of the main parts. 1...Roller shaft, 2...Bearing, 2a...Spherical surface,
3... Sleeve, 4... Cylindrical elastic body, 5... Bearing holder, 5a... Upper holder, 5b... Lower holder, 6... Annular groove, 7... Magnetic fluid.

Claims (1)

[Claims for Utility Model Registration] (1) On the outer peripheral surface of the roller shaft 1, at least both the upper and lower parts of the outer peripheral surface are centered O on the axis l of the roller shaft 1.
A short cylindrical bearing 2 formed on a spherical part 2a is fitted therein, while a cylindrical bearing holder 5 is tightly fitted into a sleeve 3 having a cylindrical elastic body 4 fixed to its outer circumferential surface. The outer circumferential surface portion of the bearing 2 including the spherical surface portion 2a is loosely fitted into the annular groove 6 formed on the circumferential surface, thereby allowing the sleeve 3 to tilt within a predetermined angular range; One of the bearing 2 and the bearing holder 5 is made of a magnetic material, and the other is made of a magnetic material, and the magnet material is formed between the spherical surface 2a of both of them and the inner surface of the annular groove 6 facing thereto. Lubricating magnetic fluid 7 that is attracted and held by magnetic force
A pinch roller is created by intervening. (2) The pinch roller according to claim 1, wherein the bearing 2 is made of a resin magnet and the bearing holder 5 is made of a resin magnetic material. (3) The bearing holder 5 consists of an upper holder 5a and a lower holder 5b which are divided into upper and lower halves with the horizontal plane where the center O of the spherical portion 2a is located as the dividing plane. Pinch roller as described.